Consider the following story. You wake up on Tuesday morning and find yourself in jail. You learn you were arrested for blowing up Bobst Library on Monday, causing millions of dollars of damage and several deaths. But you have no memory at all of what happened on Monday. The last thing you remember is going to bed Sunday night. Yet there are videotapes which clearly show you setting the bomb off on Monday, and you were arrested at the scene of the crime.
sam brown, explodingdog Further investigation reveals: the evil scientist Dr Evil has discovered a way to temporarily implant his personality and plans into other people's brains. He kidnapped you on Sunday night and did this to you. On Monday, your body awoke with Dr Evil's personality. Knowing that the effect would last only 24 hours, this person--whoever it was--spent all day carrying out evil deeds, culminating in the destruction of Bobst Library. After this person was arrested, he or she fell into a coma, and awoke on Tuesday with all of your old personality traits and complete amnesia about what happened on Monday.
Now you're on trial. There is no dispute that it was your body that did all the evil deeds on Monday. So that person--the one who committed the acts on Monday--deserves to be punished. But you think you should go free, because that person was somebody else. It wasn't you.
What do you think? Should you be punished for the acts on Monday?
Here's a second case. Suppose the jury lets you go free. Then you think, hey maybe this is a good way to get rid of my evil TA. You attempt to build a device that works just like Dr Evil's device, but your device ends up working a bit differently. Its effects are always permanent. So what you do is this. You "store" some innocent person's personality into the device. Then you go and finish off your TA. Then you sit down, right at the scene of the crime, and run the device on yourself. Now all your memories are permanently erased, you get a new personality, and so on. This is the way you plan to escape punishment.
What do you think? Should the person who's discovered at the scene of the crime be allowed to go free?
How would the conventionalist respond to these questions? He'd say, in each case, we just have to get together and decide whether we're going to call the person who committed the crimes "the same person" as the person the police have in their custody. That's all there is to it. There is no fact of the matter about whether the person in the police holding cell is responsible for the crimes, or whether this person ought to be punished. Whatever we decide to say will be alright.
This won't sound very fair to the person in the police holding cell. He thinks there is a fact of the matter. He thinks he really is innocent. It was somebody else who committed those crimes. Regardless of what people decide to say about his case.
Here's a third case. Forget about the crimes we just described. Suppose you're out hiking in the Catskills, and you come across Dr Evil's secret hideout. His henchmen capture you and put you in a cell. Dr Evil tells you that he needs to test out a new memory implant device, so that tomorrow morning he's going to "erase" all your current memories and personality, and implant new ones. (Perhaps the memories and personality of Dr Evil's young niece.) Then he'll set you free, to go about your life (or the niece's life)?
You don't mind the prospect of losing your memories and personality so much, in themselves. But you worry about whether the person with the new memories and personality will be you. You fear that it won't be you, but rather a new person in your body. You fear that undergoing this procedure will be the end for you.
It doesn't seem like it would be much comfort if your jailer told you, "Don't worry. The Committee on Linguistic Reform met to discuss such cases last week. They decided that we will all call the person with the new memories and personality 'the same person' as you."
As you're sitting in your cell in Dr Evil's hideout, you have a concern for your own continued existence. This concern doesn't seem to be addressed by linguistic decisions about how people will use the words "the same person." This is why conventionalism seems an unsatisfactory answer about what the identity of persons consists in.
How would you feel if your human husband or wife were about to be replaced by one of these puppets? Would that be bad?
Suppose that we discover how to make perfect duplicates of people. Not just clones.
These perfect duplicates are molecule-for-molecule of the original, and they have all the same beliefs and thoughts and memories as the original had (up to the time they were created).
Suppose that instead of a puppet, we're going to replace your spouse with one of these perfect duplicates. The duplicate will have the same thoughts and feelings as your spouse had, and it will sincerely believe itself to be the same person as your spouse. (It won't know about the duplication.) Would that be bad? Why?
Suppose you get eaten by a shark. Luckily we had recorded all your brain patterns a few hours earlier. So we first grow a clone of you, and then we implant these recorded brain patterns into it. This gives us a perfect duplicate of you. Some people think it's just a duplicate of you. Other people think it would really be you, resurrected.
Suppose we constructed a duplicate of you while you were still alive. You can come into the lab and meet the duplicate, talk to it, etc. You're not then in two places at once. If we prick the duplicate with a pin, you don't feel anything. This makes it look like the duplicate is just a perfect copy of you. (It was qualitatively identical to you, at the moment it was created, but it's not numerically identical to you. And as time goes by, and the copy is placed in new situations, it will have new experiences of its own, which may be different from the experiences you are having. So there will start to be more and more qualitative differences between the copy and you.) Would it be OK to die, knowing that this duplicate would carry on your life?
The conventionalist would respond to these questions by saying, we just have to decide whether we're going to call the duplicate "the same person" as you. Whatever we decide to say will be alright. That doesn't sound very satisfying. If you know you're about to die, but the duplicate will carry on your life, it's small comfort to be told, "Don't worry. The Committee on Linguistic Reform has decided that we will all call the duplicate 'the same person' as you." You're worried about whether you will still be around tomorrow. This worry just isn't addressed by people's deciding that they're going to use words in a certain way. So again, conventionalism seems an unsatisfactory answer about what the identity of persons consists in.